Which of the following is true about subatomic particles?
electrons are negatively charged and are the heaviest subatomic particle.
protons are positively charged and the lightest subatomic particle.
neutrons have no charge and are the lightest subatomic particle.
the mass of a neutron nearly equals the mass of a proton.

Option (d) is the correct answer.

Explanation:

Nucleus of an atom contains three subatomic particles. These are protons, neutrons and electrons.

Mass of a proton is kg.

Mass of a neutron is kg.

Mass of an electron is kg.

Also, protons are positively charged, neutrons have no charge and electrons are negatively charged.

Therefore, we can conclude that the mass of a neutron nearly equals the mass of a proton.

when 25.0 ml of 0.700 mol/l naoh was mixed in a calorimeter with 25.0 ml of 0.700 mol/l hcl, both initially at 20.0 °c, the temperature increased to 22.1 °c. the heat capacity of the calorimeter is 279 j/°c.

the equation for the reaction is:

naoh + hcl → nacl + h₂o

moles of hcl = 0.0250 l hcl ×

0.700

mol hcl

1 l hcl = 0.0175 mol hcl

volume of solution = (25.0 + 25.0) ml = 50.0 ml

mass of solution = 50.0 ml soln ×

1.00

ml soln

= 50.0 g soln

δt=t2-t1

= (22.1 – 20.0) °c = 2.1 °c

the heats involved are

heat from neutralization + heat to warm solution + heat to warm calorimeter = 0

q1+q2+q3=0

nδh+mcδt+cδt=0

0.0175 mol ×

δh

+ 50.0 g × 4.184 j·g⁻¹°c⁻¹ × 2.1 °c + 279 j°c⁻¹ × 2.1 °c = 0

0.0175 mol ×

δh

+ 439.32 j + 585.9 j = 0

0.0175 mol ×

δh

= -1025.22 j

δh=1025.22j0.0175 mol= -58 600 j/mol = -58.6 kj/mol

it would be d. henry moseley

hope this !

and sorry if i'm late. have a good rest of your day! : d